1. Field of Use
This invention relates generally to detonation control apparatus for an internal combustion engine, such as an outboard motor. In particular, it relates to detonation control apparatus which employs an electronic controller responsive to electric signals from a detonation (knock) sensing device to control a valve which regulates the fuel/air mixture to the engine to thereby control knock.
2. Description of the Prior Art
Premature firing of the fuel/air mixture in the cylinders of an internal combustion engine causes the mixture to explode rather than burn smoothly and this phenomena, called detonation or knock, results in loss of power and possible engine damage. Detonation occuring in large outboard motors, resulting from increases in engine speed from idling to cruise or beyond, can be reduced to some extent by adjusting engine ignition timing, i.e., by advancing the timing or spark as engine speed is increased. Typically, this is accomplished by means of a mechanical linkage connected between the engine throttle and an adjustably positionable trigger coil in the ignition system, or by means of some type of electrical or electronic spark advance control means responsive to engine speed. A technical paper No. 780155 entitled "Reduction of Octane Requirement By Knock Sensor Spark Retard System" published February 27-March 3, 1978 by the Society of Automotive Engineers, Inc. discloses an electronic spark advance control means, as does a paper No. 780413 published on the same dates by SAE.